MUDDY CANON. 411 



From the summit of the ridge, in addition to the Gasteropoda already 

 enumerated, were obtained the following : 



Ophileta complanata. 

 BapMstoma acuta. 



Prof F. B. Meek says, in his Report, referring to the genus Ophileta : 

 "One of these is a small Ophileta, scarcely distinguishable from 0. complanata 

 of Vanuxem, as described from the Calciferous sand rock of New York "; 

 and of the others, that they are "nearly allied to forms found in beds of the 

 age of the Calciferous period in Minnesota, Wisconsin, and Texas ". 



A specimen of the grayish-black, cherty limestone from the base of 

 Ute Peak was selected for chemical analysis. It is a compact, homogeneous 

 rock, with a few grains of brilliant calcite scattered through it. The anal- 

 ysis was made by Mr. B. E. Brewster with the following result : 



Insoluble residue 16.567 



Soluble silica . . - 0.164 



Ferric oxide and alumina 0.601 



Lime - 43.231 



Magnesia 2.180 



Phosphoric acid 0.118 



Carbonic acid 36.200 



Water and organic matter. 1.169 



100.230 



The carbonic acid, with the bases lime and magnesia, would yield: 



Carbonate of lime 76.82 



Carbonate of magnesia - - 4.58 



81.40 . 



The insoluble residue gave upon analysis: 



Silica 13.447 



Alumina 3.120 



16.567 

 These analyses show that the rock is a dolomitic limestone, rich in silica 



